Production of label-decorated containers comprising inserting a label in a mold and then molding a container by injection molding, blow molding, differential pressure forming or foam molding has previously been reported (see JP-A-58-69015; the term "JP-A" as used herein means an "unexamined published Japanese patent application, U.S. Pat. No. 4,986,866, EP-A-502396 and EP-A-254923). Labels to be used for this in-mold decorating, called in-mold labels, are generally made of natural pulp paper or plastic films.
Included in such label-decorated containers are those with a label containing a coupon which is to be separated from the label after the purchase of the label-decorated container.
In order for the coupon to be separated easily, the periphery of the coupon is usually perforated, and the coupon is prevented from sticking to the container by coating a parting agent on the adhesive layer at the part corresponding to the coupon or by applying no adhesive to the part corresponding to the coupon.
However, when such a coupon, being not adhered to the container, has a large area, it is apt to lift to form a blister due to shrinkage of the container after integral molding, and the poor appearance considerably reduces the commodity value.
Further, it is difficult to put a finger under the coupon to peel off the coupon.
In order to overcome the above problems, the present inventors previously proposed an in-mold label with a coupon composed of a base layer comprising a biaxially stretched film and an adhesive layer, in which a part of the adhesive layer is in a band form, and has a formation density of 50% or less to make the corresponding part of the base layer easily strippable with notches being provided at one end of the coupon on the strippable band (see Japanese Patent Application No. Hei-3-60884).
However, since the in-mold label is pressed onto the wall of a container on integral molding, the label and the container are tightly adhered with no air gap. Besides, the adhesive layer is spread nearly up to the end of the coupon from which stripping is to be started. Therefore, it is not easy to pick up the end of the coupon with one's finger nail or finger to make a hold for starting stripping. Accordingly, it was still difficult to peel off the coupon.